This invention concerns improvements in a process for continuous production of seam-welded metal, preferably steel, tubings.
In the art of continuous manufacture of seam-welded steel pipes, a steel strip stock is taken out from a strip coil and subjected to a tube-shaping step and then finally to a seam-welding step.
In this case, longitudinal edge zones including strip edges are subjected to higher plastic, tensile deformations than the remaining body part of the tubing being formed. As a consequence at the finpass zone defining the terminal of the tube-shaping step, excess, residual compressive stresses are produced in said longitudinal edge zones, while in the substantial body portion of the tubing, excess, residual tensile stresses are produced, with resultant disadvantageous invitation of buckling undulations which disturb desired optimal edge-welding operation.